Magnetic cycloid gear

Abstract

A magnetic cycloid gear includes an outer gear member comprising a first plurality of magnets that provide a first number of magnetic pole pairs, wherein the outer gear member has an outer gear member axis, and an inner gear member comprising a second plurality of magnets that provide a second number of magnetic pole pairs, wherein the inner gear member has an axis that is offset from the outer gear member axis and wherein the second number of magnets differs from the first number of magnets. The gear further includes a drive mechanism operatively coupled to rotate the inner gear member as it revolves in an eccentric manner relative to the outer gear member axis, and a constraint mechanism coupled to the inner gear member to prevent it from rotating bout its own axis as it revolves. The outer gear member rotates in response to the inner gear member revolving.

What is claimed is: 
     
         1 . A magnetic cycloid gear comprising:
 an outer gear member comprising a first plurality of magnets that provide a first number of magnetic pole pairs, wherein the outer gear member has an outer gear member axis;   an inner gear member comprising a second plurality of magnets that provide a second number of magnetic pole pairs, wherein the inner gear member has an inner gear member axis that is offset from the outer gear member axis and wherein the second number of magnetic pole pairs differs from the first number of magnetic pole pairs;   a drive mechanism operatively coupled to the inner gear member to impart a rotary motion to the inner gear member to revolve the inner gear member in an eccentric manner relative to the outer gear member axis; and   a constraint mechanism coupled to the inner gear member to prevent the inner gear member from rotating about an axis of the inner gear member as it revolves;   wherein the outer gear member is movable in a rotary manner in response to the inner gear member revolving.   
     
     
         2 . The magnetic cycloid gear of  claim 1 , wherein the drive mechanism is associated with a high speed, low torque input and the outer gear member rotary motion is a low speed, high torque output. 
     
     
         3 . The magnetic cycloid gear of  claim 1 , wherein the drive mechanism comprises a motor positioned onboard the gear. 
     
     
         4 . The magnetic cycloid gear of  claim 3 , wherein the drive mechanism further comprises an eccentric ring coupled between the motor and the inner gear member. 
     
     
         5 . The magnetic cycloid gear of  claim 1 , wherein the constraint mechanism comprises an orbital bearing assembly. 
     
     
         6 . The magnetic cycloid gear of  claim 1 , wherein the gear ratio is at least 30:1. 
     
     
         7 . The magnetic cycloid gear of  claim 1 , wherein the gear outputs a torque ranging from about 25,000 ft-lbs to about 29,000 ft-lbs. 
     
     
         8 . The magnetic cycloid gear of  claim 1 , further comprising a counterweight device positioned to adjust a center of mass of the gear to be about a rotation axis of the gear. 
     
     
         9 . The magnetic cycloid gear of  claim 1 , wherein a radial differential between an outer surface of the inner gear member and an inner surface of the outer gear member in a concentric arrangement of the gear members ranges from about 0.1 in. to about 0.6 in. 
     
     
         10 . The magnetic cycloid gear of  claim 9 , wherein the axis of the inner gear member and the axis of the outer gear member are offset from each other by an amount ranging from about 0.1 in. to about 0.6 in. 
     
     
         11 . A system comprising:
 the magnetic cycloid gear of  claim 1 ;   a high speed, low torque input shaft operatively coupled to the inner gear member of the magnetic gear;   a low speed, high torque output shaft operatively coupled to the outer gear member of the magnetic gear; and   rotary equipment associated with an oil drilling rig operatively coupled to be driven by the output shaft.   
     
     
         12 . The system of  claim 11 , wherein the rotary equipment is chosen from a top drive, drawworks, and a mud pump. 
     
     
         13 . A method of torque conversion comprising:
 imparting a rotary drive motion to an inner gear member comprising a first plurality of magnets providing a first number of pole pairs, wherein the rotary drive motion is from a high speed, low torque input;   constraining the rotary motion of the inner gear member from rotating about an axis of the first gear member, as the inner gear member is driven to revolve in an eccentric manner within an outer gear member, wherein the outer gear member comprises a second plurality of magnets providing a second number of pole pairs that differs from the first number of pole pairs; and   in response to the movement of the inner gear member, permitting the outer gear member to move in a rotary manner to provide a low speed, high torque output.   
     
     
         14 . The method of  claim 13 , further comprising converting the high speed, low torque input to the low speed, high torque output at a gear ratio of at least about 30:1. 
     
     
         15 . The method of  claim 13 , wherein in response to the movement of the inner gear member, the outer gear member rotates about an axis of the outer gear member.